/*
 * This file contains code from "C++ Primer, Fourth Edition", by Stanley B.
 * Lippman, Jose Lajoie, and Barbara E. Moo, and is covered under the
 * copyright and warranty notices given in that book:
 *
 * "Copyright (c) 2005 by Objectwrite, Inc., Jose Lajoie, and Barbara E. Moo."
 *
 *
 * "The authors and publisher have taken care in the preparation of this book,
 * but make no expressed or implied warranty of any kind and assume no
 * responsibility for errors or omissions. No liability is assumed for
 * incidental or consequential damages in connection with or arising out of the
 * use of the information or programs contained herein."
 *
 * Permission is granted for this code to be used for educational purposes in
 * association with the book, given proper citation if and when posted or
 * reproduced.Any commercial use of this code requires the explicit written
 * permission of the publisher, Addison-Wesley Professional, a division of
 * Pearson Education, Inc. Send your request for permission, stating clearly
 * what code you would like to use, and in what specific way, to the following
 * address:
 *
 *  Pearson Education, Inc.
 *  Rights and Contracts Department
 *  75 Arlington Street, Suite 300
 *  Boston, MA 02216
 *  Fax: (617) 848-7047
*/

template <class Type> class Queue
{
	// interface functions to Queue are unchanged
public:
	Queue(): head(0), tail(0) { }

	// copy control to manage pointers to QueueItems in the Queue
	Queue(const Queue& Q): head(0), tail(0)
	{
		copy_elems(Q);
	}
	Queue& operator=(const Queue&);
	~Queue()
	{
		destroy();
	}

	// return element from head of Queue
	// unchecked operation: front on an empty Queue is undefined
	Type& front()
	{
		return head->item;
	}
	const Type front() const
	{
		return head->item;
	}

	void push(const Type&); // add element to back of Queue
	void pop();             // remove element from head of Queue

	bool empty() const      // true if no elements in the Queue
	{
		return head == 0;
	}
private:
	// workaround: MS Compiler doesn't allow nested template class
	// to be defined outside the class body
	//struct QueueItem;  // forward declaration of nested type QueueItem
	struct QueueItem {
		QueueItem(const Type& t): item(t), next(0) { }
		Type item;           // value stored in this element
		QueueItem* next;     // pointer to next element in the Queue
		// MS won't allow definition outside the class so no static members
		// of nested template classes
		//static int static_mem;
	};

	QueueItem* head;   // pointer to first element in Queue
	QueueItem* tail;   // pointer to last element in Queue

	// utility functions used by copy constructor, assignment and destructor
	void destroy();          // delete all the elements
	void copy_elems(const Queue&); // copy all elements from parameter
private:
	// copy all elements from input range denoted by iterator pair
	// workaround: MS Compiler requires member templates to be
	// defined inside the class body
	template <class Iter> void copy_elems(Iter, Iter)
	{
		while (beg != end) {
			push(*beg);
			++beg;
		}
	}
};

template <class Type>
void
Queue<Type>::copy_elems(const Queue& orig)
{
	// copy elements from orig into this Queue
	QueueItem* pt = orig.head;
	while (pt) {     // last element has next pointer == 0
		push(pt->item);  // copy the element
		pt = pt->next;   // get the next one from orig
	}
}

template <class Type>
Queue<Type>& Queue<Type>::operator=(const Queue& rhs)
{
	if (this != &rhs) {
		// destroy elements on this Queue
		destroy();
		copy_elems(rhs);    // copy from rhs into left-hand Queue
	}
	return *this;
}

template <class Type>
void
Queue<Type>::destroy()
{
	while (!empty())
		pop();
}


template <class Type>
void Queue<Type>::push(const Type& val)
{
	// allocate a new QueueItem object
	QueueItem* pt = new QueueItem(val);

	// put item onto existing queue
	if (empty())
		head = tail = pt;   // queue has only one element
	else {
		tail->next = pt;     // add new element to end of queue
		tail = pt;
	}
}


template <class Type>
void Queue<Type>::pop()
{
	// pop is unchecked: popping off an empty Queue is undefined
	QueueItem* p = head;     // keep pointer to head so can delete it
	head = head->next;       // head now points to next element
	delete p;                // delete old head element
}

/* workaround: MS Complier doesn't allow member templates to be
 * defined outside the class body
template <class Type> template <class Iter>
void Queue<Type>::copy_elems(Iter beg, Iter end)
{
    while (beg != end) {
       push(*beg);
       ++beg;
    }
}

* because can't define a member oustide the class, also can't
* have static members of nested template classes
// defines an int static member of QueueItem,
// which is a type nested inside Queue<Type>
template <class Type>
int Queue<Type>::QueueItem::static_mem = 1024;
*/


#include <iostream>
using std::cout;
using std::endl;

Queue<int> queue1;

int main()
{
	for (int ix = 0; ix != 1024; ++ix)
		queue1.push(ix);

	for (int ix = 0; ix != 1024; ++ix) {
		int i = queue1.front();  // check next item
		if (i != ix)
			cout << "Something's wrong! i = " << i
				 << " ix = " << ix << endl;
		queue1.pop();   // and remove it
	}

	if (!queue1.empty())
		cout << "Queue is not empty but should be!" << endl;
	else
		cout << "OK, queue empty again" << endl;


	for (int ix = 0; ix != 1024; ++ix)
		queue1.push(ix);

	Queue<int> queue2(queue1);  // use copy constructor

	for (int ix = 0; ix != 1024; ++ix) {
		int i = queue2.front();   // check next item
		if (i != ix)
			cout << "Something's wrong! i = " << i
				 << " ix = " << ix << endl;
		queue2.pop();  // and remove it
	}

	if (!queue2.empty())
		cout << "queue2 is not empty but should be!" << endl;
	else
		cout << "OK, queue2 empty again" << endl;

	queue2 = queue1;  // use asssignment operator
	for (int ix = 0; ix != 1024; ++ix) {
		int i = queue2.front();
		if (i != ix)
			cout << "Something's wrong! i = " << i
				 << " ix = " << ix << endl;
		queue2.pop();
	}

	if (!queue2.empty())
		cout << "queue2 is not empty but should be!" << endl;
	else
		cout << "OK, queue2 empty again" << endl;

}
